Spinal surgery often requires removal of the existing intervertebral disc tissue located between adjacent vertebrae and replacement thereof with an intervertebral implant which may take the form of a cage or other fusion device or an artificial disc which may be of the type which allows limited universal movement of the adjacent vertebrae with respect to each other.
It may be desired to initially separate the adjacent vertebrae from each other and to retain them apart, prior to cleaning out the existing disc tissue and inserting the intervertebral implant. To distract adjacent vertebrae away from each other, an instrument having a pair of anchor screws, one anchored in each of the adjacent vertebrae, is typically used to move the vertebrae apart.